Shen Wanwan, a modern criminal investigator, dies while rescuing a trafficking victim and wakes up in the body of a young woman who drowned in 1990s Xuzhou City. The original Shen Wanwan had just graduated from the police academy and was set to become a criminal investigator, a profession that matches Shen Wanwan's own background. However, she inherits a life of poverty within the Shen family, an ordinary household in the Old Factory District where resources are scarce and gender bias is prevalent. Her younger brother, Shen Zhuo, is doted on by the grandmother and parents, while Shen Wanwan is expected to sacrifice for him. Determined to change her fate and improve her family's living conditions, she asserts herself against the favoritism, taking control of household resources and her brother's new bicycle to secure her own future.
Two days before her official reporting date, Shen Wanwan is summoned to the municipal police bureau for an urgent dismemberment case. She joins Team One of the Criminal Police Division, led by the sharp-tongued Captain Tao Jiang and alongside her senior colleague Cui Luo and classmate Xiang Dong. The case involves twenty-two bags of body parts discovered across the city, with no head found yet. Shen Wanwan distinguishes herself from Xiang Dong, who is physically fit but emotionally fragile when confronted with gore, by displaying remarkable composure and keen observational skills. During a search in Heping District, she notices a black plastic bag dripping blood from a clothesline outside an apartment. She investigates and discovers a severed male genitalia inside, linking the crime to the ongoing dismemberment case.
The investigation reveals that the victim is Cheng Li, a fugitive wanted for double murder seven years prior. Cheng Li had been living under an alias as a bricklayer. The case takes a dramatic turn when it is revealed that Cheng Li’s brother, Cheng Liang, a wealthy businessman with a messy personal life, was murdered three days earlier. The body parts were found at the apartment of Yang Chunling, one of Cheng Liang’s mistresses. Yang Chunling is protected by Wu Yaoming, a powerful local businessman and her benefactor, who intimidates the police into releasing her due to lack of concrete evidence.
Frustrated by the lack of progress and Yang Chunling’s defiance, Shen Wanwan returns home exhausted. That night, she mysteriously transforms into Huahua, Yang Chunling’s Pekingese dog. As the dog, she overhears Yang Chunling’s conversation with Wu Yaoming’s driver, who is secretly Yang Chunling’s lover. They discuss their affair and Wu Yaoming’s involvement, but do not reveal information about the murders. Shen Wanwan wakes up human the next morning, realizing she can transform into the dog at night. Recognizing the investigative potential of this ability, she returns to work with a secret advantage. She proposes a method to interrogate Yang Chunling that she believes will break her silence, leveraging the information she gathered while in canine form. The story ends with Shen Wanwan preparing to use her unique supernatural insight to advance the case, while Xiang Dong grows increasingly jealous of her competence and Captain Tao Jiang watches her with cautious interest.
